CVE-2023-39663Public exploitNetwork attack vector

Disputed service interruption via localization regex backtracking

Published Aug 29, 2023 · Updated Oct 2, 2024

Regular-expression denial of service in MathJax 2.7.9 and earlier allows remote attackers to interrupt browser rendering. The pattern and markdownPattern expressions in MathJax.js can backtrack exponentially when MathJax.Message.Set() or MathJax.Localization._() receives a crafted message string. MathJax disputes exploitability because those functions evaluate only library-supplied strings, leaving no supported path for remote input to reach either expression.

CVSS severity7.5
High
EPSS probability0.82%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Regular-expression denial of service in MathJax 2.7.9 and earlier allows remote attackers to interrupt browser rendering. The pattern and markdownPattern expressions in MathJax.js can backtrack exponentially when MathJax.Message.Set() or MathJax.Localization._() receives a crafted message string. MathJax disputes exploitability because those functions evaluate only library-supplied strings, leaving no supported path for remote input to reach either expression.

The record

CVE
CVE-2023-39663
Published
Aug 29, 2023
Updated
Oct 2, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-1333
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 29, 2023CVE publishedPublication date reported by the CVE source.
  2. Oct 2, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-1333Inefficient Regular Expression Complexity

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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